Citronella oil Citronella oil is an

essential oil An essential oil is a concentrated hydrophobic liquid containing volatile (easily evaporated at normal temperatures) chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the o ...

obtained from the leaves and stems of different species of ''

Cymbopogon ''Cymbopogon'', also known as lemongrass, barbed wire grass, silky heads, Cochin grass, Malabar grass, oily heads, citronella grass or fever grass, is a genus of Asian, African, Australian, and tropical island plants in the grass family. Some s ...

'' (lemongrass). The oil is used extensively as a source of perfumery chemicals such as

citronellal Citronellal or rhodinal ( C10 H18 O) is a mono terpenoid aldehyde, the main component in the mixture of terpenoid chemical compounds that give citronella oil its distinctive lemon scent. Citronellal is a main isolate in distilled oils from the ...

, citronellol, and

geraniol Geraniol is a monoterpenoid and an alcohol. It is the primary component of citronella oil and is a primary component of rose oil, palmarosa oil. It is a colorless oil, although commercial samples can appear yellow. It has low solubility in w ...

. These chemicals find extensive use in soap,

candles A candle is an ignitable wick embedded in wax, or another flammable solid substance such as tallow, that provides light, and in some cases, a fragrance. A candle can also provide heat or a method of keeping time. A person who makes candl ...

and

incense Incense is aromatic biotic material that releases fragrant smoke when burnt. The term is used for either the material or the aroma. Incense is used for aesthetic reasons, religious worship, aromatherapy, meditation, and ceremony. It may also b ...

, perfumery, cosmetic, and flavouring industries throughout the world. Citronella oil is also a plant-based

insect repellent An insect repellent (also commonly called "bug spray") is a substance applied to skin, clothing, or other surfaces to discourage insects (and arthropods in general) from landing or climbing on that surface. Insect repellents help prevent and cont ...

and has been registered for this use in the United States since 1948. The

United States Environmental Protection Agency The Environmental Protection Agency (EPA) is an independent executive agency of the United States federal government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it ...

considers oil of citronella as a

biopesticide A Biopesticide is a biological substance or organism that damages, kills, or repels organisms seens as pests. Biological pest management intervention involves predatory, parasitic, or chemical relationships. They are obtained from organisms inclu ...

with a non-toxic mode of action. Citronella oil has strong

antifungal An antifungal medication, also known as an antimycotic medication, is a pharmaceutical fungicide or fungistatic used to treat and prevent mycosis such as athlete's foot, ringworm, candidiasis (thrush), serious systemic infections such as ...

properties.

Types

Citronella oil is classified in trade into two chemotypes:Chang, Yu Shyun, 2007, ''8 Map species from Malaysia for ICS,'' Forest Research Institute Malaysia, Workshop on NFP, 28–29 May 2007, Nanchang, PR China

Ceylon type

* CAS: 89998-15-2 * CAS: 8000-29-1 * EINECS: 289-753-6 * FEMA: 2308 * CoE: 39 * Obtained from: ''

Cymbopogon nardus ''Cymbopogon nardus'', common name citronella grass, is a species of perennial aromatic plant from the family Poaceae, originating in tropical Asia. It is the source of an essential oil known as citronella oil, which is widely used for its natura ...

'' Rendle * Main components:

(5–15%),

(18–20%) and geranyl acetate (2%), citronellol (6–8%),

limonene Limonene is a colorless liquid aliphatic hydrocarbon classified as a cyclic monoterpene, and is the major component in the oil of citrus fruit peels. The -isomer, occurring more commonly in nature as the fragrance of oranges, is a flavoring a ...

(9–11%), and methyl isoeugenol (7–11%). Citronellal, geraniol, citronellol

Java type

* CAS: 91771-61-8 * CAS: 8000-29-1 * EINECS: 294-954-7 * FEMA: 2308 * CoE: 2046 * Obtained from: ''

Cymbopogon winterianus ''Cymbopogon winterianus'', common name java citronella, is a perennial aromatic plant from the family Poaceae, originating in western Malesia. Used in perfumery products and cosmetics, a source of Citronella oil Citronella oil Citronella oil i ...

'' Jowitt * Main components:

(32–45%),

(21–24%) and geranyl acetate (3–8%), citronellol (11–15%),

(1–4%). The higher proportions of

and

in the Java type oil make it a better source for perfumery derivatives. The standard quality of Java type from Indonesia is regulated by Indonesian authority under SNI 06-3953-1995, which requires

minimum 35% and total

minimum 85%. Both types probably originated from

Mana Grass According to Melanesian and Polynesian mythology, ''mana'' is a supernatural force that permeates the universe. Anyone or anything can have ''mana''. They believed it to be a cultivation or possession of energy and power, rather than being ...

of Sri Lanka, which according to Finnemore (1962) occurs today in two wild forms – ''Cymbopogon nardus'' var. ''linnae (typicus)'' and ''C. nardus'' var. ''confertiflorus''. Neither wild form is known to be used for

distillation Distillation, or classical distillation, is the process of separating the components or substances from a liquid mixture by using selective boiling and condensation, usually inside an apparatus known as a still. Dry distillation is the he ...

to any appreciable extent. Citronella oil from

species should not be confused with other similar lemony oils from '' Corymbia citriodora'' and ''

Pelargonium citrosum ''Pelargonium'' 'citrosum' (often sold by the invalid binomial name ''Pelargonium citrosum'' ) is a perennial subshrub with fragrant leaves that are reminiscent of citronella. ''P.'' 'citrosum' is marketed as "mosquito plant" or "citrosa ger ...

''.

Health questions

Direct application of citronella oil has been found to raise the heart rate of some people.

Health Canada Health Canada (HC; french: Santé Canada, SC)Health Canada is the applied title under the Federal Identity Program; the legal title is Department of Health (). is the department of the Government of Canada responsible for national health poli ...

banned the oil's use as an insect repellent in 2012 but later lifted the ban in February 2015.

World production

At present, the world annual production of citronella oil is approximately 4,000

tonne The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...

s. The main producers are

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...

and

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Gui ...

- producing 40 percent of the world's supply. The oil is also produced in

Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia, at the junction of the East and South China Seas in the northwestern Pacific Ocean, with the People's Republic of China (PRC) to the northwest, Japan to the no ...

Guatemala Guatemala ( ; ), officially the Republic of Guatemala ( es, República de Guatemala, links=no), is a country in Central America. It is bordered to the north and west by Mexico; to the northeast by Belize and the Caribbean; to the east by Hon ...

Honduras Honduras, officially the Republic of Honduras, is a country in Central America. The republic of Honduras is bordered to the west by Guatemala, to the southwest by El Salvador, to the southeast by Nicaragua, to the south by the Pacific Oce ...

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

Sri Lanka Sri Lanka (, ; si, ශ්‍රී ලංකා, Śrī Laṅkā, translit-std=ISO (); ta, இலங்கை, Ilaṅkai, translit-std=ISO ()), formerly known as Ceylon and officially the Democratic Socialist Republic of Sri Lanka, is an ...

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area, the List of countries and dependencies by population, second-most populous ...

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the List of South American countries by area, second-largest ...

Ecuador Ecuador ( ; ; Quechua: ''Ikwayur''; Shuar: ''Ecuador'' or ''Ekuatur''), officially the Republic of Ecuador ( es, República del Ecuador, which literally translates as "Republic of the Equator"; Quechua: ''Ikwadur Ripuwlika''; Shuar: ' ...

Jamaica Jamaica (; ) is an island country situated in the Caribbean Sea. Spanning in area, it is the third-largest island of the Greater Antilles and the Caribbean (after Cuba and Hispaniola). Jamaica lies about south of Cuba, and west of Hispa ...

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Afric ...

Mexico Mexico (Spanish language, Spanish: México), officially the United Mexican States, is a List of sovereign states, country in the southern portion of North America. It is borders of Mexico, bordered to the north by the United States; to the so ...

, and

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring coun ...

. The market for natural citronella oil has been eroded by chemicals synthesised from

turpentine Turpentine (which is also called spirit of turpentine, oil of turpentine, terebenthene, terebinthine and (colloquially) turps) is a fluid obtained by the distillation of resin harvested from living trees, mainly pines. Mainly used as a special ...

derived from

conifers Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All ext ...

. However, natural citronella oil and its derivatives are preferred by the

perfume Perfume (, ; french: parfum) is a mixture of fragrant essential oils or aroma compounds (fragrances), fixatives and solvents, usually in liquid form, used to give the human body, animals, food, objects, and living-spaces an agreeable scent ...

industry.

Use as a repellent

Citronella oil is popular as a natural insect repellent. Its

mosquito Mosquitoes (or mosquitos) are members of a group of almost 3,600 species of small flies within the family Culicidae (from the Latin ''culex'' meaning " gnat"). The word "mosquito" (formed by ''mosca'' and diminutive ''-ito'') is Spanish for "li ...

repellent qualities have been verified by research, including effectiveness in repelling ''

Aedes aegypti ''Aedes aegypti'', the yellow fever mosquito, is a mosquito that can spread dengue fever, chikungunya, Zika fever, Mayaro and yellow fever viruses, and other disease agents. The mosquito can be recognized by black and white markings on its l ...

'' (

dengue fever Dengue fever is a mosquito-borne tropical disease caused by the dengue virus. Symptoms typically begin three to fourteen days after infection. These may include a high fever, headache, vomiting, muscle and joint pains, and a characteristic ...

mosquito). To be continually effective, most citronella repellent formulas need to be reapplied to the skin every 30–60 minutes. Citronella candles (which burn citronella oil) are no more effective than other candles at repelling insects, and experts do not recommend it as a useful method. Research also indicates that citronella oil is an effective repellent for body lice,

head lice The head louse (''Pediculus humanus capitis'') is an obligate ectoparasite of humans. Head lice are wingless insects that spend their entire lives on the human scalp and feeding exclusively on human blood. Humans are the only known hosts of thi ...

, and

stable flies ''Stomoxys calcitrans'' is commonly called the stable fly, barn fly, biting house fly, dog fly, or power mower fly. Unlike most members of the family Muscidae, ''Stomoxys calcitrans'' ('sharp mouth' + 'kicking') and others of its genus suck bl ...

. A study conducted by

DARPA The Defense Advanced Research Projects Agency (DARPA) is a research and development agency of the United States Department of Defense responsible for the development of emerging technologies for use by the military. Originally known as the A ...

in 1963 determined that hydroxycitronellal was an effective repellent against both aquatic and terrestrial

leeches Leeches are segmented parasitic or predatory worms that comprise the subclass Hirudinea within the phylum Annelida. They are closely related to the oligochaetes, which include the earthworm, and like them have soft, muscular segmented b ...

. The US

Environmental Protection Agency A biophysical environment is a biotic and abiotic surrounding of an organism or population, and consequently includes the factors that have an influence in their survival, development, and evolution. A biophysical environment can vary in scale ...

states that citronella oil has little or no

toxicity Toxicity is the degree to which a chemical substance or a particular mixture of substances can damage an organism. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a subs ...

when used as a topical insect repellent, with no reports of adverse effects of concern over a 60-year period. Some products are applied to human skin, so EPA requires proper precautionary labeling to help assure safe use. If used according to label instructions in the US, citronella is not expected to pose health risks to people, including children and other sensitive populations. The US Food & Drug Administration considers citronella oil as generally recognized as safe ( GRAS). Canadian regulatory concerns with citronella as an insect repellent are primarily based on data-gaps in

toxicology Toxicology is a scientific discipline, overlapping with biology, chemistry, pharmacology, and medicine, that involves the study of the adverse effects of chemical substances on living organisms and the practice of diagnosing and treating e ...

, not on incidents. In the EU, Ceylon type citronella oil is placed on the category 3 list, with some safety concern regarding methyl eugenol. In the UK, EU legislation governing insect repellents came into force in September 2006, which banned citronella as an active ingredient in any insect repellent products."HSE Biocides Unit responds to The Daily Telegraph article"
13 October 2006 This applied to insect repellent for both humans and other animals. It can still be sold as a perfume, but must not be sold as an insect repellent.

References

{{Reflist, 2 Biopesticides Essential oils Flavors